A BIOPSY POLE SYSTEM FOR BOW‐RIDING DOLPHINS: SAMPLING SUCCESS, BEHAVIORAL RESPONSES, AND TEST FOR SAMPLING BIAS

The collection of biopsy samples from free-ranging cetaceans has proven useful for addressing questions regarding population and social structure (e.g., Baker et al. 1990), evolutionary relationships (e.g., LeDuc et al. 1999), feeding ecology (e.g., Walker et al. 1999), and contaminant levels (e.g., Fossi et al. 2000). In the past, modified crossbows and rifles have been used to sample both large and small cetaceans (e.g., Weinrich et al. 1991, Barrett-Lennard et al. 1996, Krutzen et al. 2002). These systems have been shown to elicit only short-term behavioral responses by sampled animals, and no physiological complications have been reported during wound healing (e.g., Weller et al. 1997, Krutzen et al. 2002). The International Whaling Commission has deemed these methods acceptable because there is no evidence of long-term detrimental effects to sampled individuals or populations (International Whaling Commission 1991). However, such techniques are not without risk. For example, the use of a crossbow has led to the death of a common dolphin (Delphinus delphis) in the central Mediterranean Sea (Bearzi 2000). Less invasive techniques to obtain tissue samples from free-ranging small cetaceans are desirable, and other methods developed for this purpose include skin swabbing (Harlin et al. 1999) and fecal sampling (Parsons et al. 1999). When selecting a sampling technique, the conservation status of the species and target population, as well as the potential behavioral response of the animals to sampling, should be considered. It is also important to assess if the research question can be answered with the amount of tissue obtained with a specific technique.